Think about it as a special court that only deals with corporate/shareholder matters.

Check with an accountant but I believe it can be a loan or shareholders equity.

Following  @Koleton Daley 's comments, I would suggest you look into the directors/shareholders/etc of the company.

@Sasha Danvilen are you looking specifically for someone to do Multi-member LLCs where the shareholders are SDIRAs or SOLO401Ks?

Could we potentially form an entity where they are the majority shareholder and use that to invest? 

Many require the LLC/S-Corp as the borrower / property owner, but will also require a personal guarantee from the individual members/shareholders of the corporation. 

@Scott Meyers The REITS are starting to do strange things due to pressure for share holders as their returns continue to diminish.

First, an LLC with shareholders could still be a syndication.

To your point about investing in public corporations, they are all structured as subchapter C corporations and pay corporate tax on income before issuing passive income in the form of dividends to shareholders.

The remaining funds will be utilized as repair reserves ($25k) + cost of design and improvements to the commercial property ($345k).The company is offering shareholders a 40% profit share in this project.